Dear Tim Roberts: Thank for your reply! As I said before for some reason,I need to implement a usb custom audio driver with a UAA-compatible usb audio device.The usb audio device works correctly with the windows usbaudio.sys. Developing a new usb audio driver replace the usbaudio.sys is my job! ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/